1. Field of the Invention
The present invention, in one aspect, relates to the field of spectroscopy, and devices and methods through which it is applied. In a more particular aspect, the invention relates to spectroscopic devices and methods using Laser Induced Breakdown Spectroscopy (LIBS) in the detection of trace metal elements in the various parts of living organism. The invention also relates to the detection of normal and malignant tissue or cancer cells using LIBS devices and methods according to the invention. The invention also relates to a method and device that can provide real-time on site measurement of trace metals in a plant or animal. It can be used to detect cancer or trace element deficiency related to other health problems in either animals or plants.
2. Related Art
U.S. Pat. No. 4,927,307 to Cremers et al discloses an apparatus and method for using Laser-Induced Breakdown Spectroscopy (LIBS) to identify contaminants in liquid samples.
U.S. Pat. No. 5,847,825, to Alexander discloses an apparatus and method for using Laser-Induced Breakdown Spectroscopy (LIBS) to examine paints and coatings.
U.S. Pat. No. 5,128,882 to Cooper et al discloses a fiber optic cone penetrometer probe to irradiate soil with UV or visible light to generate a fluorescence, reflection, or absorption spectrum of soil contaminants. The fluorescence spectroscopy described in the patent generates information for classifying certain molecular species, but does not form a plasma and is generally insensitive to atomic species, which are important to the identification of metal contamination.
U.S. Pat. No. 5,751,416 to Singh et al discloses analytical methods involving Laser-Induced Breakdown Spectroscopy (LIBS). The disclosure is limited to utilizing LIBS methodology to examine inorganic specimens in environmental applications to determine the presence materials such radioactive elements or toxic metals in off-gas emissions.
U.S. Pat. No. 6,174,754 to Theriault et al discloses a cone penetrometer involving Laser-Induced Breakdown Spectroscopy (LIBS) for soil sample analysis.
All documents cited herein are incorporated by reference for all purposes.
3. Background
The optimum concentration and balance among various trace elements is vital for the health of both plants and animals. For example, an imbalance in certain trace elements such as sodium, potassium or others can indicate a number of health disorders. In animals such imbalances can cause or be indicative of a disorder to the nervous system or decreased functioning of the brain, liver, kidney or other vital organ. An imbalance in one or more trace elements can also affect or indicate a disorder in plants at various stages of growth, either at germination, blossoming, or at another stage of growth.
Recent surveys reveal that in 2003, breast cancer will be newly diagnosed in over 200,000 women in the United States.1,2 Early diagnosis, especially before the cancer has metastasized to regional lymph nodes is essential. Breast lumps can be found by self-examining or a physical examination by a medical practitioner. Primary diagnosis is currently done using ultrasound and/or mammography tests. In the regular course of diagnosis, a breast biopsy is needed to determine whether a lump is malignant or benign. This requires that the lump, or some part thereof be first extracted by surgery and then analyzed using pathological methodology to determine whether the biopsy contains cancerous cells. Recently, imaging and molecular biology techniques have been developed for assisting with cancer diagnosis.3-5 
Existing technologies for cancer detection include radiology NMR imaging and biopsy followed by histopathological examination. Newer methods, which are still experimental include matrix assisted laser desorptionlionization (MALDI) technique, and surface enhanced laser/desorption ionization (SELDI) technique. These different methodologies are very expensive and can also require significant time for analyzing a sample in a laboratory. Current methods for definitive identification of malignancy within a breast can be a difficult and painful process because a sample from a suspicious tissue mass must be extracted and then analyzed to determine whether it is malignant.
Laser Induced Breakdown Spectroscopy (LIBS) is a method for detecting the presence of various elements in a sample by directing a high power emission from a laser onto the sample to form a plasma. The plasma is then analyzed spectroscopically to determine the composition of the sample.
The LIBS methodology, through the discovery of this invention, now offers promise as a method suitable for incorporating with a probe to detect trace metal profiles in various biological media, because it is highly sensitive and requires no sample preparation. The LIBS method can include delivery of laser energy to a sample through air utilizing high power densities to ionize a sample. According to the invention, fiber optic cable can be used successfully to obtain LIBS spectral data from a remote location allowing analysis of a sample located at a considerable distance from the excitation laser and analyzing equipment. Further information about Laser Induced Breakdown Spectroscopy (LIBS) is found in U.S. Pat. No. 5,751,416 issued May 12, 1998, and in U.S. patent application Ser. No. 10/098,368, filed Mar. 18, 2002.
In the practicing the instant invention, LIBS surpasses the demanding and expensive methodology currently associated with cancer identification and produces results at a lower cost, in less time, providing spectral profiles that correlate to classifications of cancer while at the same time eliminating many of the complexities and risks inherent in tissue analysis by biopsy. According to the invention, LIBS has additional uses than known methods of analyzing biological samples including uses for tissue identification and forensic analysis of trace elements in a biological sample.